By Khara McKeen
SUNRAY BEACH — Horseshoe crabs are among the world’s oldest and most fascinating creatures. They are estimated to be at least 300 million years old. The earliest horseshoe crab species were crawling around the Earth’s shallow coastal seas for at least 100 million years before the dinosaurs even arrived. Since that time thousands of other species have come and gone, but horseshoe crabs have survived and today remain much as they were those millions of years ago, hence the nickname “living fossils.”
The spring migration of many species of shorebirds coincides with the arrival of the horseshoe crabs in the Delaware Bay. These ancient arthropods are vital to the migration of thousands of shorebirds on route to their breeding grounds in the Arctic. Relying on masses of tiny, green eggs spawned by breeding horseshoe crabs, shorebirds descend on the Delaware Bayshores famished and at half their departure weight. Before continuing on their epic 10,000-mile journey, these amazing birds must gorge themselves on horseshoe crab eggs sloshing against the shores of the Delaware Bay.
Recent bird counts of migratory shorebirds have shown alarming decreases in numbers. Like the link between shorebird migration and horseshoe crab spawning times, many think there is a corresponding link between shorebird population declines and horseshoe crab over-harvesting.
The Nature Conservancy is assisting the University of Delaware’s Sea Grant Marine Advisory Service in an annual census of breeding horseshoe crabs in the Delaware Bayshores. TNC is conducting surveys throughout May and June on peak spawning days. A census starts just after sunset with an educational session that includes the biology of the horseshoe crab and step-by-step instructions on how to conduct the survey. Volunteers, armed with headlamps or flashlights, count the numbers of male and female horseshoe crabs using one-meter square quadrants. A typical survey usually lasts about two hours from start to finish.
Join TNC staff as the Conservancy’s Bayshores Program protects this globally important phenomenon through the annual Horseshoe Crab Census on the Conservancy’s Sunray Beach Preserve, located in Middle Township, just north of Villas.
To get involved with the upcoming 2009 survey through the Delaware Bayshores Program, please contact Khara McKeen at (609) 861-4134 or kmckeen@tnc.org
McKeen said volunteers are needed to come out in the moonlight to count crabs on the following dates and times:
• Thursday, May 7 at 9 p.m.
• Saturday, May 9 at 10:30 p.m.
• Monday, May 11 at 11:45 p.m.
• Friday, May 22 at 8:30 p.m.
• Sunday, May 24 at 10 p.m.
• Tuesday, May 26 at 11:45 p.m.
• Friday, June 5 at 8:45 p.m.
• Sunday, June 7 at 10 p.m.
• Tuesday, June 9 at 11:30 p.m.
• Saturday, June 20 at 8 p.m.
• Monday, June 22 at 9:45 p.m.
• Wednesday, June 24 at 1:30 p.m.
